AppleScript: The Definitive Guide, 2nd Edition

Script Runner

An application without facilities for editing or compiling scripts may nevertheless offer to execute compiled scripts for you on demand by way of some convenient interface, such as a menu . Such an application might be called a script runner . There is usually a requirement that a compiled script file be placed beforehand in some particular location where the script runner can find it. Because the script is compiled beforehand, a time-consuming step (compilation) is skipped, and execution typically proceeds considerably faster in a script runner than it does in an internally scriptable application where the code must be compiled from text on the fly.

Many scriptable applications act as script runners, typically by means of a special Script menu . This behavior is helpful because, having developed a script that drives such an application in a useful way, you might like some convenient interface for executing that script on future occasions; the application's Script menu provides such an interface. Scripts in an application's Script menu do not have to target that application, but the feature makes sense, and is provided, in the expectation that they will do so. (And when a script in an application's Script menu does target that application, there is sometimes a tremendous speed advantage over running that same script from elsewhere; see Chapter 22.)

For instance, as mentioned under "Customization" in Chapter 1, if you put scripts into ~/Library/iTunes/Scripts/, iTunes ...